Carbureting in internal combustion engines



. March7, 1939. E. L. MULLER H CARBURETING IN INTERNAL COMBUSTION ENGNBS Filed March 18, 1936 A v l 7 VEQ?" y' M Patented Mar. 7, 1939 UNITED' STATES CARBURETING IN INTERNAL COMBUSTION ENGINES Eugen Ludwig Mlleg Berlin, Germany Application March 18, 1936, Serial No. 69,582

' In Germany March 30, 1935 g 1 Claim.

There is a type of internal combustion engine working with compression of the mixture and with electric ignition in. which the proportion of fuel sdetermined by a pump driven by the engine. The fuel may be introduced into the induction pipe or into the cylinders through nozzles or fuel valves, which atomize the fuel very finely, when a very high pumping pressure is used. 4

According to the invention such nozzles or valves are replaced by porous bodies located in the air supply pipe, and the fuel is'forced through these in a very finely divided condition, and is exposed to the passing air over 'a large surface.

By this means extremely fine subdivision of the fuel is obtained with quite small pumping pressures, and formation of large drops is prevented. As is well known the rate of delivery of fuel during a stroke of the pump cannot be exactly adapted to the conditions of suction of the engine at different speeds and loads; so that when nozzles` are used it is impossible in some conditions of working to avoid drip of fuel after injection, or formation of drops prior to the suction stroke. The porous bodies which the invention substitutes for nozzles' exert a strong braking action on the very fine particles of fuel forced through them, *so that dripping of the fuel is prevented; and because of its bibulous properties the bodies serve as an equalising reservoir between successive suction strokes of the engine.

This equalising action also makes it possible to use a single injecto'r for several cylinders instead of one foreach cylinder. To make this clear Figures 2, 3 and 4 show in full lines the air demand of an engine plotted against its crank angle, and by broken dotted lines the fuel delivery; Figure 2 refers to a four-stroke single cylinder engine with a single cylinder fuel pump driven by the cam shaft. If the pump piston is actuated by a cam -of suitable form the fuel delivery can be adapted to the' air demand of the engine in such fashion that the mixture 'ratio of air to fuel is approximately'constant throughout the suction stroke. The broken line shows this condition. If a pump with swash-plate drive is employed for the sake of conveniently regulating the fuel delivery by varying the stroke of the pump, the delivery of the pump extends over 180 of the pump or cam shaft revolution as shown by the dotted line of Figure 2, i. e., over acomplete revolution of the engine shaft. Thus the period of injection is about twice as long as the suction stroke of the engine. With the usual nozzles this wouldlead to impossible conditions; but if a filter element is used it assumes an average condition of saturation, retains fuel when the air column is at rest, and delivers it only 5 to air which istraveling past it. Formation of drops is-avoided; the fuel is admixed' with the air in the form of a fine cool cloud.

` Figura 3 shows the conditions for a four cylinder four-stroke engine, with a swash-plate 10 driven two-cylinder pump driven from the crank shaft.

Figure 4 shows the diagrams for a four-cylinder i four-stroke engine with a four-cylinder swash-plate fuel pump driven from the cam 15 shaft The 'broken lines show the delivery by the several cylinders of the fuel pump, the dotted line the total delivery of the fuel pump.

In four-stroke engines 'with more than four cylinders and two-stroke engines with more than two cylinders the suction strokes of the several pistons will overlap, so that there is a continuous demand for fuel. i

To obtain even delivery to the several cylinders the fuel pump and its actuating mechanism should be such that the fuel delivery is in phase with the air suction.

Figure 1 shows in section an example of construction of the invention.

The housing'of the apparatus is built of two 30 parts I and 2. The air supply pipe 3 may either draw from the atmosphere or be fed by a supercharger. Between the upper and lower parts I,

2 of th'e housing is an annular filter element 4. .The fuel delivered by the controlled fuel pump is led through a tube 5 to the narrow annular space 6 between the filter element and the housing. Packng 'l and 8 prevents leakage of fuel directly into the interior of the housing. screws 9 fasten the parts l, 2 'and the filter element between them to form a rigid block.

Within the casing a stream-lined throttle cone o is arranged' for vertical movement, guided by webs ll in the lower part of the casing and a. stern I 2 in the upper part. Downward movement of the cone is limited by nuts I3, |4 by the aid of which the width of the conical annular space between the throttle cone Io and the filter element 4 canvbe exactly set, and so the proper throttle opening for satisfactory idling determined. It is of great importance' for satisfactory idling that the air required shall flow at high speed over the filter element and contact with the whole surface of the element. It is a feature of the invention that the filter element itself 55 'the drawing. At the upper end of the stem |2 is a pivot pin IE with which engages a throttle regulating rod not shown in the drawing.

In order that the force requisite to move the throttle cone maynot be too great, particularly in passing from ldling to load position, a part of the air suction and drag exerted on the throttle may be balanced by compensating springs suitably arranged upon the Operating rod, or by a pneumati'c balancer. In such a balancer the difi'erence of pressure on the two sides of the throttle may act upon a diaphragm or, as shown in the example illustrated, through a tube IT upon a piston IB, which is connected with the pin !6 through llnkwork s, 20, 2I, 22, and so opposes to the downward force exerted on the 'con o (which is also exerted on the piston 18) an upward force on the pin IS. In the drawing the cylinder 23 is shown open to the atmosphere above the piston" I& through the orifice 24. If supercharging is employed it may be desi'able to connect the upper end of the cylinder 23 with the upper part I of the housing of the apparatus. When the throttle is fully open the linkwork s, 20, 2l and the pin' IS take the position shown in broken lines and the piston I8 is at the bottom of the cylinder 23.

forms part of the throttle, for that not only Any form of filterelement, whether a porous block or a woven fabric, may be employed, sub- Ject, in the latter case, to the material being stretched upon a hollow vessel or on a suitable skeleton.

A block filter element, or the iframe of a fabrio filter may be cemented or soldered into the carburetor housing. v

The porosity and the flneness of the pores of the filter are not of great importance, since the proper proportion of fuel in relation to the air is determined by the fuel pump; for the same reason the device will continue to work even though the filter element be largely blocked up, and renewal of the element will be necessary only at long intervals. I

` Fuel pumps of moderate output pressure (say about 10 atmospheres) may be employed; and

the output pressure may in course of time fall off greatly through wear without causing failure since a pressure of about two atmospheres is ample for the operation of the device.

It is to be expected that the fine subdivision of the fuel without heating will enable engines fitted with the invention to employ considerably heavier fuels than would otherwise be possible.

I claim:

A method of forming a combustible mixture for internal combustion engines which comprises the steps of forcing the fuel under pressure through a porous body to reduce the fuel into finely divided particles in its forced passage through the porous body, and passing air past the porous body to take up and mix with the fuel and form the combustible mixture.

' v EUGEN LUDWIG 

